Your enhancement shaman's damage is terrible- 40kish lower than mine on our heroic kill yesterday (Heroic has no different mechanics that affect DPS, and infact Enhancement DPS is bugged due to a totem issue so in theory someone's DPS should be higher on normal than heroic).
His spec is wrong- he should be speccing Echo of Elements over Elemental Mastery. His reforging is poorly done and seems nonsensical- at times he reforges hit to expertise then reforges other items back to hit. He has no leg enchant. He didn't use any agility potions.
His Lightning Bolt casts are too low-they should be one of his highest priority spells, likewise his Lava Lash hits. His Flame Shock uptime sucks. So does his Searing Flames, so his uptime on Searing Totem/Fire Elemental is bad. I don't think he is using the correct priority list tbh when you take all of that into account.

Overall he is really poor, and needs guiding to a "How to Enhance" thread because I'm not convinced he knows what he's doing in raids. And from reading other comments it looks like a lot of your other DPS really need the same cos the majority of them are not pulling their weight.

Looking at your 12th attempt, the longest, you had 7 Celestial Protectors. You really should try to get that down to 5. That's 2 in the first phase and 3 in the repeat phase. If your ranged are capable of it, just have them dps the protectors while your melee stays on boss full time. Don't even have them run out to reset stacks unless they don't have any abilities to counter it (rogues, ww monks, ret pals). I actually manage to reach 23 stacks in the first phase, and I don't actually reset the debuff until the first spark is dead. This can give you considerable more time for dps in the first phase, also allowing you to only have 2 adds spawn, as that cuts down on boss dps time.

You are 6 healing it, which is fine. That gives you 17 total dps for the fight. There are 6 platforms, and you can put 3 dps per pillar almost (one pillar will end up having a tank) Put whatever melee you can on the outer pillars and have ranged in the middle, able to attack all 3 sparks if needed. Try to get the pillars down around the same time if you can, so you can get less adds in that phase. Use banners, stormlash totems, cd's on the 4th/5th sparks. Try to kill 5 sparks the first time, and you really only need 4 for the second. This will give you 11 debuffs on the boss. You also want to have everyone pushing at least 100k dps on that fight towards the end.

If you can manage 2.2m raid dps, you can kill him before the 9 minute mark.

Looking at the 12th attempt, your shadow priest seouls, seems to be using his spells out of spell priority. The Devouring plague and Mind Spike damage on Elegon could be much higher! you are only casting 14 devouring plagues and 36 mind spikes on that fight, what gives? You can easily get about 20 Devouring Plauges and 60 Mind Spikes increasing both of those spells damage by a lot. Your dot uptimes need work, I suggest downloading a dot tracker to increase those since your Vampiric Touch is only up bout 75% of the time and your Shadow Word: Pain is up 90% of the time, both of those can be improved to be up about 95% of the time or more!

Phase 2: Bro, the only spells you need for the energy charges when they are walking to the pylons is Mind Spike, Mind Blast, and Shadow Word: Death. You should be keeping dots up on elegon until he takes away the platform in phase three and on the energy charges simply Mind Spike and Mind Blast on cool down, when the charges are under 20% life hit Shadow Word: Death. I am bringin this up because it appears that you are putting Devouring Plague and Shadow Word: Pain on them which isn't necessary at all. It is also better to put Devouring Plague on Elegon during that phase.

Gear and Reforging:
Honestly, I looked at your armory and it appears you simply do not care about your character at all. There are multiple bracer upgrades for your class and using 450 ilvl bracers is ridiculous! Go Grind heroics or even spend an hour doing 2s for points with someone in trade chat or your guild. The conquest bracers aren't bad for pve since they provide some stats now. If you put Perfect Energized Alexandrite gems in your blue sockets and Perfect Quick Sunstones in your yellow sockets you can easily reach the haste cap for shadow priests as a goblin with your current gear.

Since I am on your server if you have any questions you can send me a tell or in game mail to arabus or reprisel.